Thermostatic instrument



Aug. 26, 1930.

A, G. STRAND THEVRMOSTATIC INSTRUMENT lFiled Nov. 4: 1927 v means which will be rammed Aug. 2s, 1930 UNITED STATES 'Param' ori-ics ARTHUR G. STRAND, OF MINNEAPOLIS, MINNESOIA, ASSIGNOR T SIMFLEX HEAT 1 REGULATOR COMPANY, OF MINNEAPOLIS, MINNESG'IA, A COBPORA'IIN OF MIN- NESOTA 'rnEaMosrA'rrc INSTRUMENT Application led November 4, 1927. Serial No. 231,150.

l. This invention relates to a thermostatic instrument and more particularly to a thermostatically actuated means for making and breaking contacts in electrical circuits used to control devices for regulating heating elements to control the temperature in a room or space to be heated. In such instruments the engagement of the two or more contactsl is controlled by athermostatic member usually placed in the rooms to be heated. Said member moves slowly and with a rigid bar moved by the thermostat into engagement with fixed contacts, there is a very light engagement of the bar and contacts when they first come into engagement, and just before 'they come into engagement there is, of course, a very small space therebetween. This is apt to cause sparking or arcing which is ob- "jectionable It is desirableto have a mechanism which is quite sensitive and will op- Icrate on a variation of a very few degrees of temperature. l

It is an object of this invention, therefore, to provide a thermostatic instrument comprising a contact making and breaking quite sensitive yand which will act with a quick make and break action. v

K It is another object of the invention to rovide a thermostatic instrument comprising spaced contacts and having a thermostatically moved'elongated strip of thin;I resilient material dis osed between said contacts with its flat sides directed toward the same, said strip being slightly bowed and l under tension so that 1t will snap from engagement with one contact into engagement with the other contact. v .It is more specifically an object of the invention to provide a thermostatic instrument comprising an adjustable member having l spaced contact points thereon and a thermostatically movable member comprising a comparatively narrow strip of thin resilient metal disposed between said contact points and in a plane substantially perpendicular to the axes of said points, said strip being slightl bowed and under tension, whereby it will1 snap from engagement with one lpoint, into engagement with the other, to-

of the invention will be fully set forth in the following description made in connection with the accompanying drawings, 'in which like reference characters refer to similar parts lthroughout the several 'views and in which Fig. l is a 'View in front elevation of a theriinostatic instrument embodying the present invention; I

Fig. 2 is a vertical section taken on line Qf-2 of Fig. 1 as indicated by the arrows; an

Fig. 3 is vertical section taken on line 3-3 of Fig. 2, as indicated by the arrows.

Referring to the drawings, a device is shown comprising a casing 5 adapted at its lower end to receive and hold aclock 6. Said casing has a .dat plate forming its front, and said plate has at its top portion a projecting substantially U-shaped plate 5, the front portion of which is provided with a scale 7 comprising graduations adapted to indicate degrees of heat. While these graduations can be variously designated, in the embodiment of the invention illustrated they are shown as numbered from 50 to 80 indicating temperaturesranging 'from 60 to 80 Fahrenheit. The front of the casing 5 which is in the form of a ilat plate, has a post 8 secured adjacent one side thereof, to which is attached by a screw 8a one end of a thermostat 9, said member 9 being formed of a dat strip comprising a plurality of metals, said strip being substantially semi-cylindrical in form and having a straight terminal arm 9*". A bar ll0 is attached to the end of the arm 9* and extends downward in 'front of the cas'- ing'5. The arm 10 has an inwardly projecting end 10 having a slot therethrough into which pro'uiects a-tongue l1a 'formed on the end of an elongated comparatively narrow strip 11 of lthinelastic metal, such as copper or phosphor bronze, 'the bar 10 Vbeing made of similar metal. The upper end of said .stri 1l has a shank ll projecting thron h a slot in the lower side cithe member 12,511

tion extending upward along bar 10 and riveted thereto by the spaced rivets 13, the member 12 having a portion 12b bent around the front side of thearm 9% 12 is preferably' also made of the same material as bar 10 which is quite thin and somewhat resilient, and the lower terminal arm thereof which receives the upper end of strip 11 may be bent upwardly or downwardly somewhat to place member 11 under more or less pressure. The member 11 has adjacent its central portion and secured thereto, small disks 11c forming contact members. Said member 11 normally is slightly bowed so that it is under some tension. The member has secured thereto by the screws 14 thin somewhat arcuate plates 15. A plate or block 16 illustrated as formed ot insulating material, is provided, which block has a thimble 17 secured thereto, pivoted to the casing 5 about a pivot pin 18. The block 16 carries spaced posts 19 in which are threaded the' contact screws 20 and 21 respectively, said screws being shown as having slotted heads and having reduced Contact end portions 20' and 21* respectively. rl`he posts 19 have reduced shanks extending through plate 16 and threaded to receive the clamping nuts 19. T he plate 16 has secured to its under side or the side adjacent easing 5, a pointer 22, the upper end of which is bent to move over the iront ot plate 5a and said pointer has a pointed endy co-operating with the graduations 7. rlhe plate 16 also has a small plate 23 having spaced upwardly extending arms 24 with which bar is adapted to engage. Plate 1G also has resilient arms 25 secured thereto by the nuts holding posts '19 in place, which arms extend toward casing 5 and frictionally enf gage at their ends with the plates 15. It will be seen that the member 11 is disposed between the contact points 2()a and 21a and is disposed in a plane substantially perpendicular to the surface of the plate 16 and substantially perpendicular to the common axis of screws and 21.

ln operation the device` shown is pla-ced in the room to be heated and the pointer 22 will be moved to have its point indicate on i the scale 7 the temperature which it is de.-

sired to maintain in said er 22 is moved, the block 16 swings about the airis of pivot 18 and the position of the contact members 2O and 21 is varied in relation room. lVhen pointto the strip 11 and thermostat 9. The strip 11 takes the position in engagement with either one of the contact points 2Oa or 21. lllhen the temperature changes and the thermostat 9 moves the bar 10, the member-11 will be swung at its bottom and will pass the central position in relation to bar 10 and the strip 11 at a certain point will snap out of engagement with Contact 2OZL as shown and into engagement with contact 212. When the ra strip 11 or its contacts 1I. engage one of the The member contacts 2Oa or 21, a circuit is usually closed, causing operation ot a halturevolution motor or some other motor and after the same has operated as desired, the circuit is opened so that another control operation will not take place until the contact 11c again engages the other one of the contacts 20 or 21u. lVhen the temperature again changes sulliciently the thermostat 9 will again move the bar 10 and member11 will be swung to the other side of its central position so that it will snap into engagement with the opposite contact. One of the contacts 11c is thus always normally in contact with one of the points 2Oa or 21a and does not break such engagement until strip 11 is in position to break the engagement very quickly and also quickly move into engagement with the other` contact. The strip 11 as stated is slightly bowed and under tension and this tension can be regulated by adjusting the lower terminal of the member 12. This can be raised or lowered to increase or decrease the tension on strip 11 so that it will have the desired action.

The stops 24 are provided both to keep the pointer 22 within the limits of scale 7 and to prevent a reverse action of the member 11. The stops 24 will engage the sides of bar 10 when the point of the pointer 22 is substantially at the ends of scale 7. Also, when the temperature has cooled to a certain point and strip 11 has been moved to bringr one of its contacts 11c into engagement with point 21, if unlimited movement of the/bar 10 were permitted, strip 11 would eventually be bodily carried to the left as shown in Fig. 3 and brought into engagement with contact 20". This might happen when the temperature dropped quickly and the instrumentl would then be in the wrong position for the prevailing temperature. By having. the stops 211 the bar 10 will engage the stop before this reverse action or bodily movement of the strip 11 takes place. The arms 25 have sutilcient friction against the plates 15 to hold the block or plate 16 in the position to which it is moved. The bar 10 is made of the same material as the strip 11 so that there will be no differential action of these parts due to expansion or contraction in varying temperatures.

`From the above description it is seen that f applicant has provided a very simple and eicient thermostatic instrument. The switch involved acts very quickly in making and breaking the contact and at the same time is extremely sensitive. The device in practice will operate vto move member 11 from one of the Contact points to the other with a difterence of two or three degrees in temperature. The device is simple in construction and quite positive in operation. IThe same has been amply demonstrated in actual practice and found to be very successful and efficient.

lt will, of course, be understood that vari- `carried thereby, a pointer secured at one end to said plate,

ons changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of applicants invention, which, generally stated, consists in a device capable of carrying out the objects above set forth, inthe novel parts and combinations of parts disclosed and defined in the appended claims.

1. 'A device of the class described, having in combination, a' plate mounted for swinging movement, a 'pair of spaced contact screws secured to said plate, a temperature scale with which said pointer co-operates, a thermostat, a member movable by said thermostat, a thin resilient strip carried by said member and disposed .with its/central portion between said Contact screws and in a plane substantially normal to the surface of said plate and the axes of said contact screws, said strip being slightly bowed and under tension, and stops on said plate limiting the relative movement of said plate and member.

2. A'device for regulating a heat generator having' in combination, a member having a supporting plate, a normally curved member said curved 'member being constructed and arranged to be moved to vary the curvatures thereof solely by changes in the temperature of the y gaseous medium surrounding the same, a-

.fmember secured to the other end of said curved member having spaced holding means,

a slightly bowed strip of resilient material' Y carried at its ends by said means, a pair of 4Contact members respectively disposed at opposite sides of, said strip adacentthe center thereof, said contact mem ers and strip being relatively movable whereby under the action of said curved member said strip will snap lfrom one contact to another upon a certain 'variation in ons medium.

3. A device for regulating a heat generator having in combination, a casing, a temperature indicating scale carried on said casing, a. pointer' cooperating with said scale, a thermostatie member movable only by tem perature changes of, the atmosphere, said member being secured at one end to said casing, a member 'carried by the other end of said thermostatic member having spaced means thereon, a strip of slightly bowed resilient material extending between said means and carried thereby, a pair of contacts at either side of said strip' adjacent the center thereof, said pointer being movable over said scale to indicate different tem eratures, and to change the'relationship o said contacts to said strip and 'thermostat whereby, by action of said thermostatic member, said strip will snap from one contact to another sn stantially at the temperature indicated by said pointer.

d. In a heat regulator,l a static element curved to at secured at one end to said support, said element terminating in a substantiall radial arm, a slightly bowed strip oi resilient inaterial secured atleast at one end to said arm, means for securing theother end of said strip, a pair of Contact members disposed at oppo; site sides of the medial portion of said strip, said contacts and said stri being relatively movable whereby' undent le action of said curved thermostatie element said strip will snap from one contact to another upon a 'predetermined variation in the temperature of the gaseous medium to which said thermo-- static element is subjected.

In testimony whereof I ailix my signature.

l ARTHUR G. STRAND,

the temperature of said gasef support, a thermot least a sem1-circle,v 

